Working of Step Up Chopper

Step Up Chopper

Q. Explain principle of step – up chopper with neat circuit diagram

Q. Draw a neat circuit and explain the working of step up chopper

Q. Describe step up chopper with neat circuit diagram. Draw its input and output waveforms.

Q. Describe step up and step down chopper with neat diagram.

Q. Describe step up and step down chopper.

Q. Explain principle of step up chopper with neat circuit diagram. Derive the expression of output voltage.

Circuit diagram of Step Up Chopper

• A chopper can be used to step up a dc voltage and an arrangement for step up operation is as shown in Figure (A) The step up chopper is a Type B chopper.
  

  Figure (A)

Operation of Step Up Chopper

Mode I :

• When SCR S₁ is closed at instant t₁, the equivalent circuit is as shown in Figure (B). The inductor current increases and energy is stored in the inductor, L.
• The voltage across the inductor is equal to the input do voltage V with the polarity as shown in Figure (B). The output voltage will be zero if the filter capacitor C is not used.

Mode II :

• If SCR S₁ is turned off, at t = t₁ then in order to maintain the inductor current in the same direction, there will be an induced voltage across L with a polarity as shown in Figure (C).
  

  Figure (B)

  Figure (C)

• The magnitude of this voltage is L di/dt. This voltage comes in series with the input dc voltage V.
• The total voltage across SCR S₁ is (V + L di/dt). The diode D₁ is forward biased and the stored energy in the inductance is transferred to the load.
• The inductor current reduces from I₂ to I₁ as shown in Figure (D).
  

  Figure (D)